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Link inputs, outputs and units

About 9 minutes · 3 reading + 6 practice and checks
Time includes reading, practice, and questions. Extra videos or further study are optional.
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A linear-model comparison with tables, graphs, slope and intercept interpretations, a solved intersection and a limitation note.

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What to include

  • Include input/output definitions and bounded domains.
  • Provide checked tables and labeled linear graphs.
  • Interpret rate and starting output with units.
  • Solve an intersection and verify both outputs.
  • Document a capacity-limited model and all changed-case checks.

Review and revise

Use these criteria to check your work and choose what to improve.

  • Method: applies the course-specific rules to the supplied cases with visible intermediate work.
  • Accuracy: results agree with the stated facts, units, boundaries and independent checks.
  • Reasoning: explains why the result follows and identifies a limitation or unresolved question.
  • Transfer: completes changed cases and revises the final project when a relevant assumption changes.
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Before you begin

The idea in everyday life

Original case: A fictional tank starts with 12 L and gains 3 L each minute for four minutes. t is elapsed minutes; V(t)=12+3t.

The idea

A function gives exactly one output for each allowed input. The input domain and units matter: a table of a school-day process should not silently be used for negative time or unrelated situations.

Follow along

Link inputs, outputs and units — worked practice

A function gives exactly one output for each allowed input. The input domain and units matter: a table of a school-day process should not silently be used for negative time or unrelated situations.

Original case: A fictional tank starts with 12 L and gains 3 L each minute for four minutes. t is elapsed minutes; V(t)=12+3t.

Case information

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ARecordBGiven
Original caseOriginal case: A fictional tank starts with 12 L and gains 3 L each minute for four minutes. t is elapsed minutes; V(t)=12+3t.

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  1. 1. 1. Define the mapping

    State the input, output and allowed time.

    You should see: Input: t in minutes, 0≤t≤4; output: volume in liters.

  2. 2. 2. Build a table

    Evaluate the rule for t=0,1,2,3,4.

    You should see: Outputs are 12,15,18,21,24 L.

  3. 3. 3. Read a value

    Explain V(2)=18 in words.

    You should see: After two minutes, the model tank contains 18 L.

  4. 4. 4. Check function status

    Decide whether giving two different volumes for the same t would match this model.

    You should see: One input must have one output; conflicting values require investigation.

Now change one thing

Change the starting volume from 12 L to 9 L, keeping inflow at 3 L/min. Enter the volume at t=3 minutes.

Your work

What to finish

A labeled function rule and table with domain notes.

Common mistake

Watch for this

The rule was only specified for the four-minute process.

How can I tell I understand it?

Interpret a new function value without extending the stated domain silently.

Try 3 questions

Quick knowledge check

Answer all 3 questions. Get at least 2 right and the lesson completes automatically.

Not yet passed

You’ll get an explanation for each answer. Signed in? Your results save to your account.

1For F(t)=8+2t, what is F(4)?
2What are the units of the coefficient 3 in V=12+3t?
3Why should V(20) not be reported as a verified tank volume?
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Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.

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Sources and further reading

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OpenStax: linear functions
Source & access notes · checked 2026-10-01

Web open/search showed the official page, its topic heading and relevant concept description. This is a content/source check, not a provider endorsement. Exact topic chapters were opened in web result turn 325view 0–14.

Access: Official page retrieved with the web reader on 2026-10-01; interactive tools and videos were not certified by retrieval.

Reuse: Original fictional teaching cases, calculations, questions and examples; link and short factual paraphrase only. No copied source exercises or illustrations.

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